To identify and evaluate potentially modifiable pre-hospital factors associated with better health outcomes after motor vehicle collisions, using existing county-specific data. Study Design: A series of related studies using multiple-year government databases linked to each other and to additional data using deterministic and probabilistic methods. Small-area (county) variability and changes over time will be described. Outcome analysis will use multilevel regression to account for clustered data structures (e.g., persons <counties <states <years). Setting and Participants: Census and sample data from injured Americans, as recorded in National Vital Statistics System (NVSS), Fatality Analysis Reporting System (FARS), National Automotive Sampling System (NASS), and other files. Explanatory variables: Structural and process variables describing local trauma systems by county (or related ZIP code) including: Levels of EMT capability;state trauma system characteristics;traffic safety legislation in effect;mean distance from air ambulances or trauma centers;mean EMS response and transport times for fatal traffic crashes. Variation in these potentially modifiable factors will be reported with respect to measures of geography, demography, and driving exposure;changes over time in a county will be considered further evidence of a locally modifiable factor. Outcome Measures: Population-based traffic mortality (NVSS/FARS);crash-based mortality, length of hospitalization, and time lost from work (NASS);and survival of FARS subjects other than the first fatality (FARS). Outcomes will be modeled as possible functions of the above pre-hospital explanatory variables (especially those identified as modifiable), while controlling for fixed geographic/demographic factors and random personal/event factors. PUBLIC HEALTH RELEVANCE: This project presents an opportunity to assemble data already available and apply contemporary statistical methods to evaluate the pre-hospital component of trauma systems. By combining data from multiple sources and controlling properly for the effects of variables at different levels of aggregation, the proposed project will provide valuable information to policy makers and trauma system managers about system improvements that can benefit individuals, particularly those living in rural areas.